I'm not 100% sure i understand what you are asking.
In the globals you can specify the yahoo smtp server int he $WAGLOBAL_Email_Server setting.
to change the port, edit the following line in the WA_UniversalEmail/WAUE_contact_1.php file:
$WA_MailObject = WAUE_Definition("".($WAGLOBAL_Email_Server) ."","25","","","","");
change the 25 to the the port you wish to use.